This invention relates to a modular optical system for making spectroscopic measurements. The particular embodiment of the invention disclosed is an infrared Fourier-transform spectrometer system which can maintain the infrared beam in a vacuum.
A book entitled Introductory Fourier Transform Spectroscopy by Robert John Bell (Academic Press 1972) contains a chapter describing commercially available optical Fourier-transform spectrometers. The spectrometers described in this chapter are limited in that they were all designed and constructed for a few particular modes of operation. Thus an experimenter who wished to rearrange the elements making up one of these spectrometers into a configuration more suitable for his requirements was faced with the difficult task of redesigning the optics of the spectrometer. An experimenter might wish to investigate the spectral characteristics of a particular beam source and for this purpose a sample chamber is not needed. However it is impossible to remove the sample chamber from one of the prior-art spectrometers and connect the detector unit in its place without redesigning the optics of the spectrometer.